The main opposition party turned up the heat on the nation's spy chief Wednesday to resign over his decision to disclose a summit transcript containing late South Korean President Roh Moo-hyun's controversial remarks on the disputed Yellow Sea border with North Korea.

Monday's disclosure of the transcript has thrown rival political parties into a fierce argument over whether Roh actually made remarks undermining the legitimacy of the sea border, called the Northern Limit Line (NLL), during his 2007 summit with then North Korean leader Kim Jong-il.

Roh proposed building a "peace and cooperation zone" over the NLL, according to the text. The ruling Saenuri Party has denounced the remarks as undermining South Korea's sovereignty.

"Disclosing and criticizing remarks made by a president during a summit meeting is something that doesn't happen in a normal country," Rep. Kim Han-gil, the chairman of the Democratic Party (DP), said at a Supreme Council meeting.

On Tuesday, National Intelligence Service (NIS) chief Nam Jae-joon defended his decision to disclose the transcript, saying he did so in order to defend the honor of his agency in the face of opposition claims that the text could have been fabricated.

The NIS had shown several ruling party lawmakers an excerpt of the transcript last week.

"Is Nam really the chief of our NIS? Is there only the NIS' honor? What about our country and our foreign relations?" DP lawmaker Shin Kyoung-min said.

Rep. Woo Won-shik, another Supreme Council member, called on Nam to step down and apologize.

The allegations about Roh's remarks were first raised by a ruling party lawmaker ahead of last December's presidential election when Roh's former chief of staff, Moon Jae-in, was running as the opposition party's presidential contender.

North Korea has never recognized the NLL, which was drawn unilaterally by the U.S.-led United Nations Command when the 1950-53 Korean War ended. Pyongyang has long demanded that the line be drawn farther south.

Last week, the opposition party sued Nam for showing the excerpt to ruling party lawmakers in what they claimed was a violation of NIS laws.

Asked whether Nam could be summoned for questioning in the case, Justice Minister Hwang Kyo-ahn left open the possibility.

"The prosecution doesn't (conduct investigations) sloppily," the minister told a parliamentary legislation and judiciary committee meeting. "If necessary, (we will) summon him." (Yonhap News)